Hierarchy of operators

The Priority or Precedence of operator is the order in which the operators are to be evaluated, written in a expression is called the Hierarchy of operators.

The associativity specifies the operator's direction to be performed, it may be left-to-right or it may be right-to-left.

Table: Priority of operators - Highest to Lowest
Priority Operator Description Associativity
( ) Parentheses left-to-right
++ , -- Pre-increment/pre-decrement right-to-left
sizeof Determine size in bytes right-to-left
* , / , % Multiplication, division, modulus left-to-right
+ , - Addition, subtraction left-to-right
< , > , <= , >= Relational less than, less than or equals to,
greater than, greater than or equals to
left-to-right
== , != Relational is equal to/is not equal to left-to-right
++ , -- Post-increment/post-decrement right-to-left
&& Logical AND left-to-right
|| Logical OR left-to-right
?: Ternary conditional right-to-left
= -= += >= <= Assignment right-to-left

Example 1: Program to explain operator precedence.

#include<stdio.h>
void main()
{
    float r;
    r = 1.0 + 2.0 * 3.0 / 4.0;
    printf("\n%f",r);
    r = 1.0 / 2.0 + 3.0;
    printf("\n%f",r);
    r = (1.0 + 2.0) / 3.0;
    printf("\n%f",r);
    r = (1.0 + 2.0 / 3.0) + 4.0;
    printf("\n%f",r);
}
2.500000
3.500000
1.000000
5.666667